1. Field of the Invention
The present invention relates generally to methods of performing surgical bone transplants. More particularly, the present invention relates to techniques by which donor allograft vertebral bones and intervertebral discs may be transplanted into a recipient patient to treat degenerative disc disease of the cervical, thoracic, and/or lumbar spine.
2. Background Discussion
Osteochondral allografts have a long history of clinical success in the treatment of articular cartilage defects in the knee, shoulder, hip, and ankle The principal advantage of the technique over all other techniques of cartilage restoration is the maintenance of an intact interface between the bone and cartilage of the graft and the preservation of the cartilage architecture; the allograft bone is placed in such a way that it heals to the bone of the recipient.
Spinal degenerative disc disease is the second most common cause of disability and a major cause of lost work days in the United States. (Morbidity and Mortality Weekly Report. 2001; 50:94-97) The economic impact of this disease is staggering, accounting for an estimated 149 million days of lost work per year due to low back pain in the United States (H.R. Guo, et al., Am J Public Health, 1999; 89(7): 1029-1035). The estimated cost is between $100 billion and $200 billion per year, mainly due to decreased productivity.(Katz, JN. Bone Joint Surg (Am), 2006; 88 Suppl. 2:21-24). The strategies for the treatment of degenerative disc disease in most cases do not involve surgery. However, should such treatment fail, surgical treatment consisting of nerve decompression and discectomy may be indicated. In more severe cases of disc degeneration or in cases associated with deformity, spinal arthrodesis (fusion) or disc replacement has been advocated. The advantages of fusion are the high rate of clinical success in pain relief and in the correction of deformity. The disadvantage is in the risk of adjacent segment degeneration.
Disc replacement has been developed over the past 20 years and has recently been approved by the United States Food and Drug Administration. The long term results of this procedure are unknown. Furthermore, as the procedure is performed through the anterior approach, revision for failure is an exceedingly dangerous procedure. Additionally, the generation of particular wear debris adjacent to the great vessels may bring up some catastrophic complications.
Spinal discs are similar to articular cartilage in their composition from collagen, proteoglycans, and water. As such, disc allograft transplants have been performed with some early success in the cervical spine as published by Luk, K.D., et al (Spine, 2003; 28(9): 864-869). The present invention applies principles learned from fresh osteochondral allograft procedures to the treatment of spinal disc degenerative disease. The objective of the procedure is to maintain segmental motion with a fresh or frozen allograft bone-disc composite, taking advantage of the avascular properties of the disc and achieving rigid fixation to the host vertebral bodies on both sides of the allograft.